Thread: Trouble with constructors and destructors in classes

Code:

Im working on a a circle class program in which I have to find the diameter and area of the circle. I have divided the program into 3 files, 1 main.cpp 1 circle.cpp and 1 circle.h
My code produces and error:

1>main_Circle.obj : error LNK2019: unresolved external symbol "public: __thiscall Circle::~Circle(void)" (??1Circle@@QAE@XZ) referenced in function _main
1>main_Circle.obj : error LNK2019: unresolved external symbol "public: __thiscall Circle::Circle(double)" (??0Circle@@QAE@N@Z) referenced in function _main
1>C:\Users\RKLO\documents\visual studio 2010\Projects\Rectangle class2\Debug\Rectangle class2.exe : fatal error LNK1120: 2 unresolved externals


Here is my code


//Cirlcle.h
#pragma once
//Circle class declaration

class Circle
{
	private:
		double radius;
	
	public:

	Circle(double=0);
	Circle (const Circle &);
	~Circle();
	
	void setRadius(double);
	double getRadius()const;
	double getDiameter()const;
	double getArea()const;
};

//Circle.cpp

//Implementation file for Circle class

#include "Circle.h"//Needed for the rectangle class
#include<iostream>//Needed for the cout
#include<cstdlib>//Needed for the exit function
using namespace std;

//sets the value of the member radius


void Circle::setRadius(double r)
{
	if (r>=0) {
		radius=r;
	}
	else {
		cout << "Invalid radius\n";
		exit(EXIT_FAILURE);
	}
}

//returns the value mamber of the variable radius
double Circle::getRadius()const
{
	return radius;
}
//returns the value member of the variable Diameter
double Circle:: getDiameter()const
{
	return 2*radius;
}
//get area returns the pruduct times pi*radius^2

double Circle:: getArea()const
{
	return 3.1416*radius*radius;
}

//main_Circle.cpp

#include <iostream>
#include "Circle.h"//Neede for the rectangle class
using namespace std;

int main()
{
	Circle box;
	double radiusCircle;//Local variable for radius
	cout<<"This program will calculate the area of a\n" ;
	cout << "circle. What is the radius? ";
	cin>>radiusCircle;
	
	box.setRadius(radiusCircle);
	
	cout << "Here is the circle's data: ";
	cout << "Radius: "<<box.getRadius()<<endl;
	cout << "Diameter "<<box.getDiameter()<<endl;
	cout << "The Area of the Circle is "<<box.getArea()<<endl;
	
	return 0;
}


Any help will be really appreciated
I have uploaded the three files for your convenience.

To re-ellaborate on what Xupicor is saying... You didn't write a default constructor.

Code:

Circle() { };

Once you write a constructor C++ stops making a default for you. Since your code in main calls

Code:

Circle box;  //Doesn't exist no Circle() function in class Circle (You wrote Circle(double=0))

you get an error. You have to write Circle(double=0) as Circle() to get your code to work. Plus you never defined Circle(const Circle &) or Circle(double=0) anyways so yeah, they don't work if they have no definition :P

Simply put, change Circle(double=0) to Circle() { } and define Circle(const Circle &) in the Circle.cpp file....

Thanks guys I fixed my program it worked really nice.

Code:

Here is my fixed code for the benefit of anyone:

//Circle.h

#pragma once
const double pi=3.1416;
class Circle 
{
private:
	double diameter,area,radius;
public:

	Circle(double=0.0);
	Circle(const Circle&);
	~Circle();
	void SetDiameter(double);
	void setArea(double);
	void setRadius(double a);
	double getDiameter()const;
	double getRadius()const;
	double getArea()const;
	void printData()const;

};//end class

//Circle.cpp
#include "Circle.h" //needed for the class
#include<iostream>//needed for the cout
#include<cstdlib>
using namespace std;

void Circle::setRadius(double r)
{
if(r>0){
	radius=r;
}
else{
	cout<<"Invalid Radius\n";
	exit(EXIT_FAILURE);
}

}//end set radio
void Circle::setArea(double a)
{
	area =a;
}//end set area

void Circle::SetDiameter(double d)
{
	diameter=d;
}//end set diameter

double Circle::getRadius()const
{
	return radius;
}//end getRadius

double Circle::getArea()const
{
	return pi*radius*radius;
}//end getArea

double Circle::getDiameter()const
{
	return 2*radius;
}//end getDiameter

void Circle::printData()const
{
	cout<<"Radius: "<<getRadius()<<endl;
	cout<<"Diameter: "<<getDiameter()<<endl;
	cout<<"Area: "<<getArea()<<endl;
	cout<<endl;
}//end printData

Circle::Circle(double)
{}//end constructor

Circle::Circle(const Circle & instance)
{}//end constructor

Circle::~Circle()
{}//end destructor

//main_circle.cpp

#include<iostream>
#include<cstdio>
#include<cctype>
using namespace std;
#include "circle.h"

int main()
{
	Circle box1,box2;
	char e;
	double r,CirArea,CirDiam;
		
	do{
	cout<<"This program will calculate the area of a \n";
	cout<<"Circle; What is the radius?"<<endl;
	cin>>r;
	box1.setRadius(r);
	box2.setRadius(r);
	box2.printData();
	cout<<endl;
	
cout<<" The Area of the Cirlce is: "<< box1.getArea() <<endl<<endl;
cout<<"Type any non-digit character to exit"<<endl;
cout<<"Press any number to continue and then hit Enter"<<endl;
cin>>e;
	
	//box1.getArea();
	//box1.getDiameter();


	cout<<"This program will calculate the area of a \n";
	cout<<"Circle; What is the radius?"<<endl;
	cin>>r;

	box2.setRadius(r);
	box2.printData();
	cout<<endl;

cout<<"Type a non-numeric value to exit"<<endl;
cout<<"Press any number to continue and then hit Enter"<<endl;
	cin>>e;	}while(isdigit(e));

	system("pause");
	return 0;
}//end main

I uploaded the files for the benefit of the user.